Photoshop Filter and Tool Tutorials
All Tutorial Text & Images - Copyright © 2011 KHI, Inc.
Using the Photoshop CS Color Channels Palette
Photoshop's "Channels" palette window allows you to edit, save, and copy individual color channels data in either the RGB, CMYK, or Lab color space. This can be useful if there is a particular problem with over-saturation in a single color channel, causing an unwanted color-cast. By modifying only one channel you are leaving intact all of the subtle shadow and highlight pixel data in the remaining channels. This technique can be used instead of the Color Balance tool which can be more destructive to subtle detail at the extreme ends of the tonal range.
The default setting for the Channels palette shows individual channels in grayscale, not in their "actual" color, but you can view each channel in its unique color by checking the "Color Channels in Color" radio box in "Display & Cursors" preferences. This will not necessarily aid in your ability to edit each channel but you will certainly know which one you are dealing with.
RGB & CMYK Color
Individual channels can be toggled on and off using the "eye" buttons, and you can view all of the channels while editing only one by clicking the RGB, CMYK, or Lab eye while only one channel is selected (CMYK sample below). This method allows you to subtly airbrush, burn, or dodge individual colors without disturbing the data contained in other channels.
Lab Color Space
The "Lab" color space uses three channels with the "L" dimension representing luminance, "A" representing the Red/Green," and "B" representing the "Yellow/Blue" color-opponent dimensions. Lab color channel editing is helpful when you want to make subtle adjustments to the tone and contrast levels while leaving all of the color information unchanged. In addition, there is no pixel loss when converting back-and-forth between the LAB and RGB or CMYK color space.
Alpha Channel Masks
Selection masks can be permanently stored as Alpha Channels, which use significantly less disk space than other mask types. This can be especially useful with very large files that can consume hundreds of megabytes. To create an Alpha Channel option-click (Mac OS) or Alt-click (Windows) on the "New Channel button at the bottom of the Channels Palette window.
Note: The following hardware and software was used in this tutorial: An Apple Mac Pro desktop computer, a Wacom Intuos 6x8 drawing tablet, Adobe Photoshop CS-CS5 photo editing software and a properly calibrated monitor.
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